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Automaticity
aka...?
Definition?
Found in..?
aka rhythmicity
Ability to build up and discharge on electricial stimulus w/o outside stimulation
Found in SA node, AV junction and purkinje fibers
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Excitability
aka...?
Definition?
Found in..?
Irritability
Ability of cell to respond to an outside stimulus. Related to ionic imbalance across the membrane of cells.
Found in all cells
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Conductivity
Definition?
Found in..?
Ability of cardiac muscle to conduct the impulse to an adjacent cardiac cell and is an electric property
Found in all cardiac cells
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Contractility
Mechanical ability of a muscle cell to shorten (contract) in response to electrical stimulus
Extensibility (stretch) vs elasticity (recoil)
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What is the normal pacemaker of the heart?
Sinoatrial (SA) node
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What is the SA node's property?
What is the regular heart rate that the SA node produces?
What does it look like on the ekg?
Automaticity
60-100bpm
No waveform on EKG
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What are the 3 P situations that could cause a decrease or increase in heart rate produced by the SA node?
Physiological (i.e. Temp) which increases demand
Pathological (i.e. V-tach) causing the runs
Pharmacological (i.e. OD on drugs)
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What is the purpose of the atrioventricular (AV) node?
To delay impulse slightly, allowing atrial kick to occur and contribute ~30% towards EDV.
This protects the ventricles from excessively rapid atrial rates.
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What is the name of the electrical connection b/w atria and ventricles?
What is it's inherent heart rate?
Bundle of His
40-60bpm
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Where does one look on the EKG to determine AV conduction dysrhythmia (heart block)?
PR segment
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What is the name of the terminal portion of conduction system, which carries impulses out into ventricular muscle tissue?
Purkinje fibers
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What are the four ions that create electrical activity on an EKG?
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What is the normal duration of the P wave?
2 3/4 squares, or 11 secs
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What is the normal duration of the PRI?
3-5 small squares, or .0.12-.0.20 secs
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P wave reps __________ depolarization while qRs reps _______ depolarization
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What is the normal duration of the qRs complex?
0.06-0.12 secs (1.5-3 squares)
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What does the ST segment represent on EKG?
ST variations usually represents one of which two events?
Early repolarization
- ST depression = ischemia
- ST eleavation = injury
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What does the T wave represent on the EKG?
What is it's voltage criteria on Lead II and Lead MCL1?
Vetricular repolarization
- Lead II: 5mm
- Lead MCL1: 10mm
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What does the QTI represent on EKG?
What are the 3 factors that can cause variations on the QTI?
Total ventricular depolarization and repolarization
Age, gender, HR
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If a U wave is present on EKG, what does it represent?
Late repolarization of purkinje fibers
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What is the 6 second method?
What is the best scenario to use this method?
Count # of qRs complexes within a period of SIX seconds (30 large boxes) and multiply by 10 = X BPM
Use for highly irregular rhythm
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What is the large square R-R method?
What is the best scenario to use this method?
Count # of large squares b/w two consecutive R's and divide into 300
(1 box = 300.... 2 = 150.. 3 = 100... 4 = 75... 5 = 60... 6+ = <60 bradycardia)
Use for regular rhythms
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What is the small square R-R method?
What is best scenario to use this method?
Count # of small squares b/w two consecutive R's and divide into 1500... is most accurate than other methods
Use when rhythm is regular
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What are the 3 components to dysrhythmia interpretation?
- 1. Impulse origin site (i.e. ventricular rhythm)
- 2. Rate of impulse (i.e. VT)
- 3. Window dressing (i.e. ACS)
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List the 7 window dressings that may occur on an EKG and its interpretation.
- 1. Shape of P wave (atrial enlargement?)
- 2. Length and patterns of PRI (heart block? max limit of 5?)
- 3. Width and shape of qRs (conduction delays?)
- 4. ST segment elevation/depression (ACS? Ischemia? Injury?)
- 5. T wave shape and direction (electrolyte abnormalities?)
- 6. QTc duration (pharm. intervention? Upper limit of 11?)
- 7. Extra beats - wide (ventricular), narrow, early or late
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What is required on an EKG to be considered a sinus rhythm? (3)
What is ST, SR, and SB?**
- 1. P waves present
- 2. P waves all look similar
- 3. 1:1 ratio of P:qRs
- ST >100bpm
- SR: 60-100bpm
- SB: <60bpm
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What are the 3 possible EKG situations to be diagnosed for having a junctional rhythm?
What is the junctional rhythm (JR) HR?
- 1. Inverted P wave in front of qRs and short PRI
- 2. Inverted P wave behind the qRs (ST segment)
- 3. No P wave at all
JR: 40-60bpm
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What are the 4 requirements for diagnosis of ventricular rhythm?
- 1. Usually no P wave
- 2. qRs always WIDE >0.12 secs (3 boxes)
- 3. Increased amplitude, bizarre-shaped
- 4. ST and T wave abnormalities
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What are 5 scenarios of ventricular rhythm and its HR (if applicable)?
- 1. VF - total chaotic activity
- 2. TdP - 150-250bpm
- 3. VT - 100-200bpm
- 4. IVR - 20-40bpm
- 5. Early ventricular beats (PVC's)
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What are the 4 requirements for diagnosis of AV conduction dysrhythmias?
- 1. P waves present
- 2. P waves all look similar
- 3. More P waves than qRs complexes (2 & 3 degree block)
- 4.Establish P to P interval in order to establish relationship of P's to each other (proves its coming from SA node)
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How would one differentiate the 4 AV conduction dysrhythmias: 2nd Deg TI, 2nd Deg TII, 2nd Deg 2:1, 3rd Deg?
Look at PR segment --> Looks same --> 2nd Deg TII and 2nd Deg 2:1 --> Has 2 P waves for each QRS --> 2nd Deg 2:1
Look at PR segment --> Looks diff --> 2nd Deg TI and 3rd Deg --> Ventricular rhythm irregular -->2nd Deg TI
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What are the 4 (1 each) requirements for diagnosis of atrial rhythm?
- 1. No isoelectric line b/w qRs complexes (AT)
- 2. AT with P/T waves becoming one and rate of 160-240bpm
- 3. Aflutter - sawtooth formation at rate of 250-350bpm
- 4. Afib - low voltage undulations at rate >350bpm
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In general, of the 5, which 2 are possible rhythms if no P waves are present on EKG?
SR, AR, AV blocks, JR, VR
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What is alpha1, beta1, and beta2's actions?
- Vasoconstriction
- Inc'd HR, conduction, contractility
- Bronchodilation
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What are the 4 best diagnoses in which one would use epinephrine?
- VF
- Pulseless VT
- Asystole
- PEA
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What is the dosing of Epinephrine for IV, IO, and ET?
IV and IO: 1mg q3-5mins, no MAX (for IV, follow with 20ml NS flush)
ET: 2-2.5mg, add 10mls NS, no MAX
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What are the four indications for using Vasopressin (same as Epi)?
- VF
- Pulseless VT
- Asystole
- PEA
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How does one dose Vasopressin during a cardiac arrest situation?
- Single use only
- 40 Units IV or IO as alternative to 1st or 2nd Epi dose
- May return to Epi 10 mins after Vasopressin dose if still pulesless
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What is the dosing of Amiodarone during cardiac arrest?
300mg IVP in 20-30ml soln total --> Repeat in 3-5mins with 150mg IVP in 20-30ml soln total
- Post-code infusion: 900mg/500mls D5W
- -->1mg/min x6h
- -->Then 0.5mg/min x18h
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What is the dosing of Amiodarone during stable tachy?
Rapid inf: 150mg diluted in 50-100ml soln over 10mins
--> Followup in 10-15mins with 900mg/500mls with initial rate of 1mg/min x6h --> Maintain with 0.5mg/min x18h
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What is the biggest precaution w/using Amiodarone?
May prolong QTI, so dont give routinely with other QT-prolonging drugs
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What is the dosing of Lidocaine for cardiac arrest? What is the max dose?
1.5mg/kg IVP, repeat q3-5mins with same or 1/2 dose.
ET: 2-2.5x the above dose, diluted in 10ml NS
Post-code: 1g/250ml with range of 2-4mg/min
Max: 3mg/kg
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What is the dosing of Lidocaine in stable tachy? What is max dose?
1mg/kg IVP then repeat in 5-10mins with 0.5mg/kg IVP
Then follow up with 1g/250mls with range of 2-4mg/min
Max: 3mg/kg
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What is the biggest precaution with using Lidocaine?
CNS toxicity like slurred speech, muscle twitching, seizures, altered loss of consciousness
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What are the 3 indications for using Procainamide?
- Ventricular ectopy
- VT w/a pulse
- Stable wide QRS complex tachy with uncertain origin
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What is the dosing for Procainamide?
LD of 17mg/kg @20-30mg/min
Then followup with 1g/250mls at 2mg/min
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What are the 3 indications for emergency use of Mg?
- Torsade de Pointe (TdP) - 1st line
- Pulseless VT
- Pulseless VF
- ^3rd line to latter two when refractory to Amiodarone and Lidocaine
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What is the dosing of Mg? What is max dose?
1-2 GRAMS IV/IO diluted in 10ml soln over 1-2mins
Max: 2gm
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What is the DOC for bradycardia?
Atropine
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What are the 2 requirements for using Atropine?
- 1. HR<60bpm
- 2. Pt is symptomatic - hypotension, chest pn, nausea, diaphoresis (excessive sweating)
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What is the dosing for Atropine? What is max dose?
0.5mg IVP, repeat dose q3-5 mins with max of 3mg
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Atropine works BEST in which type of symptomatic bradycardia?
Narrow QRS complex bradycardia
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What are the two classes of drugs, and 4 miscellaneous drugs that will work on narrow QRS complex tachycardia? Which drug is 1st line?
- 1. CCB
- 2. BB
- 3. Adenosine
- 4. Digoxin
- 5. Procainamide
- 6. Amiodarone
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What is the dosing of Adenosine? What is max dose?
6mg IVP over 1-3 secs --> Repeat with 12mg q1-2mins -->Repeat with 12mg q1-2mins -->Max dose: 30mg
**Flush each bolus with 20ml NS
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Which pressor drugs may be used for SBP<70, SBP of 70-100, and SBP >100, respectively?
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What are the three activities dealing with monomorphic VT management? (very general)
- 1. Loading dose
- Amiodarone (150mg)
- Lidocaine (1mg/kg)
- 2. Follow w/Cont. Inf
- Amiodarone (1mg/min)
- Lidocaine (2mg/min)
3. Electrical intervention - Sedate, then synchronize with 100 Joules
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Just like treating VT with pulse, what are the three drugs used, in addition to which other drug that may be included in choice of tx?
- Amiodarone
- Lidocaine
- Procainamide
Adenosine
Then synchronize at 100J
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In which 2 scenarios would one choose Adenosine or CCB/BB during a narrow complex tachycardia situation/
Regular rhythm, rate>160bpm --> Choose Adenosine
Irregular rhythm, rate >100bpm --> Choose CCB/BB
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What are the steps to take in dealing with a pt having narrow complex tachycardia (NCT)?
- 1. Regular/irregular rhythm --> Give Adenosine or CCB/BB
- 2. Sedate pt
- 3. Synchronize with 50J
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What are the steps to take in dealing with a pt having symptomatic bradycardia?
- 1. Atropine: 0.5mg q3-5mins, max 3mg
- 2. Transcutaneous Pacer (TCP, external pacemaker) at 80bpm
- 3. If pacer not available or above 2 doesnt work (BP still low), try:
- DA drip at 400mg/250ml with range of 5-20microgrm/kg/min (beta range), or:
- Epi 2-10mcg/min
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What is the immediate general tx for ACS (ST elevation)?
- MONA
- 1. Morphine 2-5mg IV if BP<90
- 2. Oxygen at 4L/min
- 3. NTG (SL, patch, nasal) if BP>90
- 4. ASA 325mg, chewable
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What are the basic interventions for the following high, med, low risk groups?
ST elevation and BBB
ST depression or T wave inversion
Normal/non-diagnostic changes in ST/T
- 1. ST elevation - cath lab, reperfusion strategy (angioplasty, stents)
- 2. ST depression - adjunctive pharm Rx (Nitro, BB, plavix, heparin)
- 3. Nondiagnostic changes in ST/T - observation (serial ECG's, enzymes, ST segment monitoring) and workup
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After intubation, what else should be done for the pt immediately after?
8-10 breaths/min, asynchronized with chest compressions.
Without the tube, 30:2
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W/o giving specifics, what is the plan for dealing with cases of pulseless VT/VF?
- 1. CPR
- 2. Shock @360J
- 3. IV/IO drug
- 4. Intubate
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What are the 2 DOC in a pulseless VT/VF situation after shocking the pt? What are the dosings?
- 1. 1mg Epi (w/20ml NS flush) q3-5mins
- 2. 40Units IVP Vasopressin ONCE, may repeat Epi after 10mins
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In a pulselessVT/VF situation, after giving Epi or Vasopressin, there are 3 other drugs that may be alternated w/shocking the pt. What are they, and what is the dosing?
1. Amiodarone 300mg diluted in 20mls total soln, q3-5mins. Then 900mg/500mls at 1mg/min x6h, then 0.5mg/min x18h
2. Lidocaine, 1.5mg/kg q3-5mins, then 1g/250ml at 2-4mg/min
3. Magnesium, 1-2g IV over 2mins and diluted in 10ml solution
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What are the 2 1st-line meds for use in a PEA pt? What are the dosings?
- 1. Epi 1mg IV over 3-5mins
- 2. Vasopressin 40Units IVP once, wait 10 mins until give Epi
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What are the 5 H's that causes PEA, and the basic solutions to each?
- 1. Hypovolemia - give NS
- 2. Hypoxia - intubate
- 3. H ion (acidosis) - oxygenate, perfuse, buffers
- 4. Hyper/hypokalemia - cant be fixed in code blue
- 5. Hypothermia
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What are the 5 T's that causes PEA?
- 1. Toxins
- 2. Tamponade (cardiac)
- 3. Tension pneumothorax
- 4. Thrombosis, coronary (ACS)
- 5. Thrombosis, pulmonary (PE)
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What are the 2 tx options for pts w/asystole and the dosing?
- 1. 1mg Epi IV q3-5mins
- 2. 40U Vasopressin IVP once, wait 10 mins until give Epi
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**Post-cardiac arrest: What is your immediate priority after ROSC (return of spontaneous circulation)?
- Optimize ventilation and oxygenation
- Ventilate at 10-12 breaths/min -->Titrate to target PETCO2 of 35-40mmHg
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**Post-cardiac arrest: If SBP<90mmHg, how would you treat it?
Give IV/IO bolus of 1-2L NS
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**What type of pt would you not induce hypothermia to?
Responsive pt
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**When dealing with a stroke pt, what would you do when your hospital has no CT machine?
Divert to hospital with a CT scanner
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**While defibbing a pt, would it be a good idea to run oxygen across the pt's chest?
No, causes fire
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**How would you suction (??)?
Suction on the way out, <10 secs
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**Which scale would you use in a suspected stroke pt?
Cincinnati pre-hospital stroke scale: Facial droop, arm drift, abnormal speech
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What are the 4 ACLS drugs that may be adminstered ET'ly?
"LEAN"
- Lidocaine
- Epi
- Atropine
- Naloxone
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